Radioactive iodine is used in imaging to help clinicians diagnose your child’s thyroid condition.

The thyroid gland needs iodine to produce thyroid hormones. The follicular cells of the thyroid have channels or pores to actively absorb iodine for making thyroid hormone. Radioactive iodine takes advantage of the fact that thyroid cells and thyroid cancer cells absorb iodine; therefore, it has been used to diagnose or treat various thyroid disorders.

Iodine is made into two radioactive isotopes, I-123 and I-131, that are commonly used in patients with thyroid disease. A radioactive isotope is a substance that gives off radiation. RAI is given by mouth, in pill or liquid form. RAI is then absorbed by the thyroid cells and can be used to diagnose or treat thyroid problems.

I-123 is most frequently used to take pictures of the thyroid gland. The dose of I-123 is small, and because of its short half-life (about 12 hours), there are fewer precautions that need to be taken. The disadvantage is that the small dose is not as sensitive at detecting thyroid tissue compared to the larger dose of I-131 that is used for treatment.

To learn more about how to prepare for this imaging test and what to expect during the exam, click here.